Some  fixes

Main contribution is to make sure we use luma and luminance correctly and derive them using the same white-point and gamma compensation, based on Sebastian's implementation. I think it's better to have this consistent than simple, to avoid weaknesses in later analysis.

Alternatively, I could derive luma coefficients for the Y part of the matrix but that only works on a true gamma function without linear segment, which we currently don't use.

I also added interesting (not duplicated by other measures) CAM attributes mainly for personal curiosity, but maybe it helps in our evaluation too.

The Griscom space is not a very good match, it's probably not Lab - just leave it out if not desired, we have Juergen's BCP.